1986 420SEL Maintenance Questions

[jodeven]

Hi all,

Plan to do some maintenance on my car next week. Vehicle has 90,000 miles. The car runs okay. Just trying to prevent major problems. Plan on replacing s. plugs, timing chain or guides or tensioner, Drive shaft flex joints, belts, front and rear brakes. Have some questions:

• Timing Chain: Do I just replace the upper guides or do I need to also change the tensioner and chain?
• What are the best plugs. Platinum or nickel?
• Best source for quality parts?

Thanks, and have a great holiday season

Joe